While it is desirous to provide an auditory or visual indicator in the passenger compartment of a vehicle to warn of brake failure or damage due to excessive wearing of the brake liners, there is considerable difficulty in connecting electrical equipment to the brake assembly because of the confined space in which a disc brake assembly is disposed. One solution is to mount a warning contact plug to a holding angle which is screwed, on its part, to a projection of the brake housing. Anchoring the holding angle has, however, the disadvantage that additional costs associated with machining the projection to provide a threaded bore. Moulding a holding device to the brake housing projection may be uneconomical, for example, when a brake which is already being series manufactured has to be retrofitted with a warning contact plug.